Poor Cooling Performance in a Vehicle with Dual A/C

CONDITION: Poor cooling performance in a vehicle with a dual (front/rear) A/C system. The system uses a joint type expansion valve* in the rear cooling unit, with no magnetic valve. The compressor has been confirmed to be ok, and the front expansion valve was replaced recently.

CAUSE: The thermosensitive tube of the rear expansion valve has become loose and is not reading the evaporator outlet temperature accurately. This caused the expansion valve to open more than necessary, and caused more refrigerant to flow to the rear cooling unit.

CORRECTION: Access the thermosensitive tube of the rear expansion valve and secure it tightly to the appropriate groove on the low-pressure tube of the rear cooling unit. Consult the manufacturer’s service information to meet proper insulation requirements.

*May also be seen in various models which have similar system configurations (e.g. 2001 – 2007 Toyota Sequoia).